The present invention relates generally to a digitizer and in particular to a digitizer having a mask for reducing the affects of stray light.
Digitizers convert optical densities of an image on a data medium to a digitized signal representative of the image recorded on the data medium. Such digitizers generally include an illuminator and a light sensitive element. The illuminator provides light that is directed towards the data medium. The light sensitive element accumulates photons based on the various optical densities of various portions of the recorded image on the data medium. The light sensitive element converts such accumulated photons into an associated analog electric charge. Electric processing circuitry accepts such an analog signal and converts it to a corresponding digital signal. The digital signal may be stored, retrieved, transferred, and processed in any variety of ways similar to other electronic data.
The light sensitive element in such a digitizer typically has a fixed field of view. When reading data from a data medium that has a width less than an associated length of the illuminator, excess illumination occurs beyond the edges of the data medium yielding undesirable flare. This flare may adversely affect the performance of the light sensitive element and hence the quality of the overall digitizing process. Some masking mechanisms have been developed to mask the outer edge of the illuminator based on a width of the data medium to be digitized. However, such methods linearly transport the mask between the illuminator and the light sensitive element requiring a complex mask transport system. In addition, there is not a simple and efficient way to automatically position the mask based on the width of the data medium. Accordingly, there is a need in the art for a simpler and less expensive masking mechanism to reduce flare where the mask is rotated about a central axis.
A digitizer for digitizing a data medium consistent with the invention includes: an illuminator configured to generate light directed towards the data medium to be digitized; and a mask configured to rotate about a central axis, wherein a portion of the mask affects a portion of the light from an associated portion of the illuminator depending on an amount of rotation of the mask from a base rotation position.
According to another aspect of the invention, there is provided a method of reducing flare from an illuminator during digitizing of a data medium that includes the steps of: generating light directed towards the data medium; and rotating a mask about a central axis a predetermined amount from a base rotation position, wherein the mask affects a portion of the light from an associated portion of the illuminator depending on the predetermined amount of rotation from the base rotation position.
According to a further aspect of the invention, there is provided a digitizer for digitizing a transparent data medium in a medical application including: an illuminator configured to generate light directed towards the transparent data medium to be digitized; a mask configured to rotate about a central axis, wherein a portion of the mask affects a portion of the light from an associated portion of the illuminator depending on an amount of rotation of the mask from a base rotation position; a lens configured to direct the light; a light sensitive element configured to convert the light directed from the lens into an analog signal representative of data recorded on the data medium, wherein the light sensitive element has a width substantially equal to a maximum width of the data medium; and electronic processing circuitry coupled to the light sensitive element, the circuitry configured to convert the analog signal into a digital signal representative of data recorded on the data medium.
According to a further aspect of the invention, there is provided a digitizer for digitizing a transparent data medium in a medical application including: an illuminator configured to generate light directed towards the transparent data medium to be digitized; a mask configured to rotate about a central axis, wherein a portion of the mask affects a portion of the light from an associated portion of the illuminator depending on an amount of rotation of the mask from a base rotation position; a light sensitive element configured to convert the light beam directed from the lens into an analog signal representative of data recorded on the data medium; and electronic processing circuitry coupled to the light sensitive element, the circuitry comprising an analog to digital converter configured to convert the analog signal to a digital signal, the digital signal having at least 16 bits of significant digits.
According to a further aspect of the invention, there is provided a digitizer for digitizing an image on a data medium including an illuminator configured to generate light directed towards the data medium to be digitized; a mask; and a page width guide mechanically coupled to the mask, wherein movement of the page width guide causes an associated movement of the mask.